Liquid blasting



May 112, 1936. E. yl SMWH 2,040,715

LIQUID BLASTING Filed June lO, 1955 ..1 IIII IIYIIA Mika/v- /NvENTo/z ez )vo V sM/-rn force.

, etc. 'I'he use of water,

abrasive Patented May l2, E93

NT]A oFFicE,

LIQUID BLAs'nNG Elmo v'. smith, Evanston, nl'. Application June 1o. 1935, serial No. 25,888 9 claims. d, (ci.` s 111) This invention relates to liquid blasting and more particularly to a method of'blasting with abrasive in which liquid is employed as a motive In the art of abrading and cleaning, ithas been customary to use steam or air as-the `motive power for projecting the abrasive or cleaning substance. The use of water is more desirable than steam or air in that it costs less, prevents silicosis, washes back the abrasive to a point where it may be again employed, avoids burning the surfaces being abraded, provides better vision for the operator for blasting purposes has been generally regarded as impracticable becauseA of the apparent necessity of using a large volume of 'water for the small In only a few `eases has an at.- tempt been made to use water for motive power and these attempts have been unsuccessful.

An object of the present invention is to provide a blasting methodin which a relatively small quantity of liquid is employed to project a relatively large amount of abrasive. A- further object is to provide a method by which a solid stream of water or other liquid,leither hot or cold, and under high pressure, is employed to project abrasive or other materials against surfaces to be abraded or cleaned.

I have discovered that an extremely small stream of water or other liquid, when projected with su'iciently high pressure, and in a substantially solid stream, can be employed to impart its velocity to a relatively large quantity of granular fed about the periphery of the stream and confined in close relation to its periphery for a suincient interval to direct the abrasive in the same direction or path followed by the stream. In other words, a pencil-like stream underl pressures in excess of say, six hundred pounds,can deliver a larger `volurne of abrasive when the abrasive 'is supplied about the periphery of the stream and is confined for the most part in con-- tact with such rapidly moving periphery long enough for the abrasive to be. directed forwardly into a path parallel with that of the stream.

I have found it desirable to introduce the sand or other abrasive `about the periphery of the method provides the largest area of contact between the abrasive and stream, and also because the substantially solid core of water seems to serve as a piston for grinding the l into the surface'under treatment. If the sand particles were fed to the movhowever, or other liquid l portion il communicating pipe portion adjacent end ing stream without means for confining the particles, there would be a tendency fory the sand grains to y off at angles from the stream while at the same time, striking other sand grains and preventing them from coming into contact with the stream. relation to the liquid'stream for a brief interval, the grains which contact 'the stream and are hurled forwardly andoutwardly are directed into a path parallel with that of the stream so that the stream andabrasive move forwardly with substantially equal velocity'and are uni-directional.

Various types of apparatusmay` be employed in conjunction with my method. For the purpose of illustration, I have shown one form of apparatus in which the method may be satisfactorilyused, which apparatus is shownin the accompanying drawing, in Which- Figure 1 is a broken sectional View of apparatus in which the method embodying my invention water inlet at a point where it opens into the suction chamber.

In the illustration given in Fig. 1, A designates a bi or hopper for sand or other suitable material; B,

pipe; and C, a regulatable discharge pipe or blast or spray gun.

The bin A may be of any suitable'construction. In the illustration given, the bottom wall il) of the bin is centrally aperturedfat l l. An outlet tting l2 is provided with awcircular ange i3 which is secured to wall l0'. The fitting is provided with a vertical pipe portion i4 Ahaving its bore aligned with the opening I l of bottom Wall l 0. The fitting I2 is provided with a horizontal pipe with the pipe portion i4 and being closed at one end I8. .If desired, the I8 may be provided with an air intake opening i9, and a valveclosure 2Q threadedly engages the pipe in such a manner as to control the admission of air through inlet opening i9.l The horizontal pipe1 portion l'l is also provided with a free end 2l to'which a rub'- ber tube 22 or other form of conduit may be attached.

The blast or spray gun C may also be of any suitable construction. The uid inlet' casting 24 comprises a handle or fluid inlet portion 25 and a horizontal pipe portion26. 'I'he handle portion 25 is provided with a longitudinal bore 25a and is tapped at its lower end to receive the attachment plug 21. Plug 21 is provided with a By confining al1 of the sand in close portion 30 ofthe inlet member 24.

side also with a longitudinal 600 to 1500 pounds or more,

shank 42B. adapted to be received within fluid inlet tube 29. The horizontal pipe portion 2 threaded at its forward end 30 and is provided adjacent the To the rear of the valve seat is an annular shoulder 32 adapted to serve as a packing retainer. The rear end of pipe 25 is closed by plug 33 which threadedly engages the end of the pipe. The plug 33 is centrally `apertured and is provided interiorly with threads 34 adapted to engage threads 35 on the valve stem 35. The valve stem 36 is provided on its inner end with a valve head 31, and at its outer side with a control knob 38. A packing 39,

The discharge piece C is also'provided with an interior threaded Member 4| is sion 42 adapted to engage the -tapered opening 43, the opening 43 merging with a passage 44 of substantially uniform diameter. Passage .44 opens into a large central suction chamber 45. Integrally formed with the casting 4l is a vertical extension 46, the extension 45 providing a vertical passage 41 communicating with the end of extension 46 is equipped ridges 48. At an intermediate point. .the extension 46 is provided with an air slot 49 controlled by an adiustable sleeve 50 threadedly engaging a portion of the extension 4B. The forward end of casing 4I `is recessed at 5l discharge tip 52. The tip 52 is provided with an annular flange 53 received within a recess 54 of a retaining ring 55. The retaining member 55 threadedly engages a reduced end portion of member 4l at 56, thus tip 52 to be -removed and replaced when desired. The discharge tip 52 is provided with a tapered passage at 51 which merges into a substantially straight passage 5B.

In the modificationA shown in Fig. 2, the discharge piece 4l is substantially the same as discharge piece 4I of Fig. l, except that the discharge passage 58' of Fig. 2 is much larger than the pas'- sage 58 of Fig. l, thus permitting liquidto be discharged from the inlet passage chamber 45Il and passage 58" without touching the walls of the discharge piece.

In the modification illustrated in Fig. 3, the discharge piece is providedwith a casting portion 42b affording a liquid inlet 44, the periphery of which is'increased by grooves or riiling 30. The slots or riiiing 6l) adjacent the main passage 44" produce a liquid stream of the same general outline as that illustrated in may be utilized to deliver a greater quantity of granular abrasive.

In the operation of the process, water or other suitable liquid is forced under high pressures, say through the channel 25a and discharge. port 44 and thence through chamber 45 and'passage 53. In the illustration shown in Fig. 1, the passages 44 and 58 are so proportioned that the stream substantially seals the outer portion of passage 58 so that the suction is produced withinchamber 45. The suction in the chamber 45 aids in drawing abrasive from container A through conduit B.

In the construction shown in Fig. 2, the passage 53 is much larger than the inlet passage forward end with a valve seat 3l. f

enclosed between two retaining members 40, is supported adjacent shoulder 32.

, if desired, may

top of suction chamber 45. The upper with retaining to receive a rubberl danger of Fig.v 3. Such a Ywater stream has an increased surface area which other abrasive is forced through conduit B into the chamber 45B.

In the operation of either of the discharge pieces C, the sand or other abrasive may be fed by pressure or by any other suitable method. It will be observed that in the operation, there is substantially no wear of the nozzles.

As an illustration of a specic operation of my method, the following may be stated. Water under a pressure of '100 pounds was passed through a circular inlet one-eighth of an inch in diameter into a suction chamber, and thence out through a discharge tube aligned with the inlet, the diameter of the discharge tube being iive-sixteenths of an inch. Dry sand was sucked through a conduit communicating with a container `as'illustrated in Fig. 1; The one-eighth inch stream successfully carried fifty pounds of sand per minute, discharging the sand against the surface-to be abraded while using only veight gallons of water per minute.. Thel above process was used for effectively removing mill-scale from nickel-steel plates as fast and as as well as such plates are cleaned with dry sand air blast machines. cleaning castings, the water served the additional function of removing core sand. The removed core sand and the granular abrasive were carried back by the water stream to a drain where the sand and abrasive were reused.

In the use of air, there is a tendency for thesurface being treated to burn and thereby to become discolored. Also, the cloud of dust particles from the surface and from the abrasive tends to obscure vision as well as increasing the silicosis. Steam likewise increases the difhculty of handling, danger from` scalds and danger due to interference with vision. It does not tend to reduce dust. It loses its force quickly on leaving the nozzle and has no washing effect. In contrast with the use of air and steam, I find that water, when employed as described heretofore, accomplishes as much while also washing the surface and permitting the recovery of abrasive. There are also the additional advantages mentioned of preventing the burning of surfaces abraded, giving better vision, preventing silicosis, lower cost, etc.

As far as my knowledge goes, I find that prior attempts to use water have failed because too great a quantity of water was found necessary.l The use of an annular stream of water enclosing the core of sand would require too great a quantity of water for the amount of sand carried. This method also cushions the impact and prevents abrasion. The forcing of water under relatively low pressures would result'in an excessive use of water. On the other hand, if a relatively small stream is passed under high. velocity through a discharge piece with the body vof water forming a substantially solid stream and the periphery of the stream being brought into. contact with sand or other abrasive and maintained in contact for an interval, a great quantity of sand can be eifectively handled, the water being small in volume but sufficient to serve the purpose of projecting the abrasive and washing the surface.'

lWhile in the foregoing specification, I have suggested certain specific pressures as desirable,- it will be understood that the invention may be employed under various conditions with changes -in such pressures to accommodate the process to diiferent classes of work, vwhile till employing v 2,040,715 the invention. Also, it will be understood that the dimensions suggested in the illustrations are for the purpose of illustration only, and wide variations can be made therefrom while utilizing the invention.

The foregoing detailed description has been given for clearness of understanding only, and

no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

I claim:

1. A method of the character set forth for blast-treating a surface, comprising: passing a non-expansive liquid in a confined stream discharged under pressures in excess of 600A pounds per square inch through the central portion of a tubular member thereby maintaining a space between said stream and member, and supplying within said space to the periphery of said stream within said tubular member-a coating of granular abrasive. I

2. A method of the character set forth for blast-treating a surface, comprising: passing a non-expansive liquid in a confined stream through the central portion only of the bore of a tubular member and discharged under pressures in excess of 600 pounds, andl supplying a coating of granular abrasive to the periphery of said stream within said member.

3.A method of the character set forth for blast-treating a surface, comprising: passing a non-expansive liquid in a conned stream and under pressure through a loading zone in which granular abrasive is drawn to the` periphery of said stream, and supplying granular abrasive to said zone, said stream body being passedthrough said zone under suiiiciently high pressures in excess of 600 pounds per square inch to carry said abrasive as a coating on its periphery without substantial penetration of said stream.

`stantially annular stream of 4. A method of the character set forth for blast-treating 'a surface, comprising: 'discharging against said surface a composite stream having an outer coating of granular abrasive and an inner core of liquid. said stream being discharged under suicient pressure to maintain said inner core substantially unpenetrated by said abrasive.

5. A method of the character set forth for blast-treating a surface, comprising: discharging against said surface a composite stream body discharged under pressures in excess of 600 pounds per square inch and having its components traveling substantially at the same velocity, said stream having an inner core of liquid and an outer coating of granular abrasive, said outer coating being substantially unmixed with said liquid. f

6. The method of blast-treating a surface comprising: impinging against said surface a stream of liquid externally coated with granular abrasive and discharged under 600 pounds per square inch.

7. The method of blast-treating a surface, comprising: traversing said surface with a subgranular abrasive, said abrasive carrier being discharged under pressures in excess of 600 pounds per square inch.

8. 'I'he method of blast-treating a surface, comprising: traversing said surface with a substantially annular stream of granular abrasive, said abrasive being carried by `a liquid core discharged under pressures in excess of 600 pounds per square inch.

9. 'Ihe method of blast-treating a surface'com- IJ prising discharging against said surface under pressures in excess of 600 pounds per square inch a confined stream of liquid substantially unmixed with solids and externally coated with a granular abrasive.

ELMO V. SMITH.

pressures in excess of 

